Field of the Invention
The invention relates to an exhaust line assembly for a bottle attachment apparatus for handling liquids, and to a bottle attachment apparatus for handling liquids.
Description of Related Art
In the case of bottle attachment apparatuses for handling liquids, the focus is on precisely measuring and conveying liquids from a storage bottle or another storage container, wherein precise measuring is performed when a partial volume of liquid is received from the storage bottle or similar into the apparatus and/or when a partial volume of liquid is externally dispensed from the apparatus into a container.
Bottle attachment apparatuses of the type being discussed are in particular bottle top dispensers and burets. Bottle attachment apparatuses of this type are widely used in chemical, biological, and pharmaceutical laboratories and production facilities.
The term “liquid” in the present context preferably refers to liquids as are used in chemical, biological, and pharmaceutical laboratories and production facilities etc. These are preferably liquids having a relative viscosity of up to about 300 (viscosity relative to the viscosity of, water, measured at normal conditions). In colloquial terms, the liquids are thus preferably those in the range of very low viscosity to slightly viscous.
In the case of bottle attachment apparatuses of the type being discussed, high requirements are set for volume accuracy of liquid intake and/or liquid dispensation, and for operator safety. The bottle attachment apparatuses are usually operated manually or else are driven by an actuator.
A typical example of a bottle attachment apparatus in the form of a bottle top dispenser is known from European Patent Application EP 0 542 241 A2. The present invention proceeds from this prior art. For bottle attachment apparatuses in the form of bottle top dispensers, the entire content of European Patent Application EP 0 542 241 A2 is incorporated by reference.
In an exemplary manner, a bottle attachment apparatus in the form of a burette is known from European Patent Application EP 2 799 141 A2 and corresponding U.S. Pat. No. 8,142,738 B2. A bottle attachment apparatus in the form of buret has many construction details in common with a bottle attachment apparatus in the form of a bottle top dispenser. Also to this extent, the entire content of EP 2 799 141 A2 and corresponding U.S. Pat. No. 8,142,738 B2 is hereby incorporated by reference.
Here and hereunder, a bottle attachment apparatus is always described in the operating position thereof, that is to say in the position thereof when fastened to a storage bottle or similar, and when aligned in a substantially vertical manner. A valve block assembly for such a bottle attachment apparatus is also described in a corresponding manner, that is to say likewise in the operating position thereof, that is to say when installed in a bottle attachment apparatus in the operating position thereof.
A substantial component part of a bottle attachment apparatus of the type being discussed is the cylinder-and-piston assembly with the aid of which the liquid may be suctioned and exhausted again. Said cylinder-and-piston assembly has a cylinder which defines a longitudinal direction, and a piston which is guided in a sealed manner in the cylinder so as to be longitudinally displaceable. In the event of an upward movement of the piston out of the cylinder, the liquid is suctioned by forming negative pressure in the cylinder. In the event of a downward movement, the liquid in the cylinder is exhausted again from the cylinder. The flow of the liquid during suctioning, on the one hand, and during exhausting, on the other hand, is directed by valves of the valve block assembly. The cylinder-and-piston assembly is connected in a sealing manner to the valve block assembly and to the lines which are located therein. The valve block assembly as such in turn is attached onto the storage bottle or similar with the aid of a fastening assembly.
An intake valve which allows liquid to be suctioned from the storage bottle by means of an intake pipe is located in the valve block of the valve block assembly. The intake pipe, most often in the form of a push-fitted tube, extends deeply downward into the storage bottle. An exhaust line extends away from the valve block in an approximately horizontal manner. An exhaust valve sits in the exhaust line or in the valve block, so as to be at the beginning of the exhaust line. In some instances, the exhaust line has an additional switching valve by way of which a return flow line leading back into the storage bottle may be opened or closed. At the opening from which the liquid exits, the exhaust line may have a closure.
Since the exhaust line protrudes from the valve block in an approximately horizontal manner and the previously discussed switching valve also often sits there, this is that side from which an operator works on the bottle attachment apparatus. This side may be referred to as the “front side” of the bottle attachment apparatus. The opposite side is the “rear side” of the bottle attachment apparatus. In the case of an electronic design embodiment of a bottle attachment apparatus, a display having corresponding operating elements is preferably located on the front side of the bottle attachment apparatus.
The fastening assembly for fastening the external housing and/or the valve block assembly of the bottle attachment apparatus onto a storage bottle or similar is often a thread assembly which is similar to a union nut, or is an internal thread which is incorporated into the valve block per se, for screwing onto the external thread on a bottleneck of the storage bottle (see the prior art mentioned at the outset). However, in principle other fastening assemblies, such as bayonet systems or short-stroke collets are likewise employable, as are systems of the type of a taper-ground joint, which are usual in laboratories.
The present focus is on the exhaust line assembly for a bottle attachment apparatus of the type being discussed. As has been mentioned, this exhaust line assembly is attached to the valve block assembly and/or to the external housing in a replaceable manner, and overall protrudes forwardly. An outrigger-type mount which most often is designed so as to be arcuate, an exhaust line which is disposed and guided in the mount and which terminates in an exhaust tip, and a mounting lug which is most often fastened to the mount and has a closure cap, by way of which the tip of the exhaust line is closable, attached to the end side thereof, so that no further liquid may inadvertently drip from the exhaust tip are part of the exhaust line assembly.
In the prior art from which the present invention proceeds (European Patent Application EP 2 799 141 A2), the mounting lug is a narrow, elongate and readily flexible material strip of a suitable plastics material. This material strip is attached to the mount of the exhaust line assembly such that the former in the case of the closure cap being removed from the tip of the exhaust line hangs down in a substantially vertical manner (having the closure cap attached to the lower end). The closure cap as such is captively fastened to this material strip, but is rotatable about the longitudinal axis thereof in case the closure cap has to be fastened onto the tip of the exhaust line using a rotational movement. To this end the material strip has an eyelet which in an exemplary manner is located in an encircling annular groove in the closure cap. This is the particularly secure design of the tip and of the closure cap which is usual today. If this here is a simple plug connection which is also known per se, the closure cap of course does not have to be rotatably mounted on the mounting lug.
The mounting lug of the exhaust line assembly is normally composed of a plastic which is suitable for the specific application, preferably of a plastics resistant to chemicals. In order for the closure cap in the case of an opened tip to be located outside the region of flow of the liquid flowing from the tip, the mounting lug is fastened to the mount such that the mounting lug automatically folds down when the closure cap is released and hangs down in a substantially vertical manner. In order for the tip to be closed, the closure cap is moved to the top, the mounting lug being deformed in an arcuate manner here.
If and when the closure cap remains on the tip over a prolonged period of time, the mounting lug which is composed of plastics begins to plastically deform to a certain degree. The mounting lug then retains a slightly curved shape even when the closure cap has been removed from the tip of the exhaust line. As opposed to the original intention, the closure cap, on account thereof, moves closer to the region at the lower end of the mounting lug in which the liquid flows from the tip, i.e. the operating region. This interferes with the handling of the bottle attachment apparatus.
If and when the closure cap impacts anywhere in an uncontrolled manner, splashing of potentially toxic or caustic liquid adhering to the closure cap may arise. At least, the closure cap protrudes into the operating region in which the container which receives the dispensed liquid is located and is pushed aside in a yielding and resilient manner. The liquid here may make its way to the external side of the container and consequently also to the handle region of the closure cap. The unwanted result is contamination of the operator's hand and a carryover of the liquid to other objects.
On account of the mounting lug being deformed in a more or less arcuate manner, flexural stress which causes friction in the eyelet-and-groove connection and impedes rotatability of the closure cap at the end of the mounting lug arises in the mounting lug when the closure cap in the closed position sits on the tip. Friction may be so intense that the eyelet is conjointly rotated, the material strip is warped, and rotatability is completely blocked.
Bottle attachment apparatuses of which the tip is disposed so as to be very high on the mount are also to be found in the prior art. The push-fitted closure cap lies above the material strip which is deformed in an arcuate manner. The arc of the material strip then even impedes manual releasing of the closure cap, and the back of the hand may contact the arc during the rotational movement.